I fully agree, LESS support is one of the few things I really would want added in PHPEd.. Even just syntax highlighting will make it better, but since it's basically just CSS with a twist, the code completion shouldn't be too difficult to throw in with it.

For now I've associated .less files with the CSS processor so I get some syntax highlighting going on, but it would be nice to have something that can trigger LESS > CSS compile when you edit the LESS file.